There is known a so-called tubular arrester for limiting overvoltages in an electric power line (cf. High voltage techniques. Ed. D. V. Razevig, Moscow, “Energiya” Publishing House, 1976, p. 287). A main element of the arrester is formed by a tube made of an insulating gas generating material. One end of the tube is plugged with a metal lid having an inner rod electrode fastened thereon. A ring-form electrode is located at an open end of the tube. A gap between the rod electrode and the ring-form electrode is called an inner, or arc quenching gap. One of the electrodes is grounded, while the second electrode is connected, via an external sparkover gap, to a conductor of the electric power line.
A lightning overvoltage results in a breakdown of both gaps, so that an impulse current is shunted to the ground. After the overvoltage impulse through the arrester has terminated, a follow current continues to flow, so that a spark channel transforms into an arc one. Due to a high temperature in a channel of the alternative arc current inside the tube, an intensive gas emission takes place providing a strong pressure increase. Gases, by flowing to the open end of the tube, create a longitudinal blowing, so that the arc is quenched when passing its zero value for the first time.
After a plurality of actuations of the arrester, the discharge chamber of the tube wears out. The arrester stops functioning properly and needs a replacement, which means an increase in maintenance costs.
There is also known an arrester for limiting overvoltages in an electric power line, the arrester being based on the use of a protective sparkover air gap formed between two metal rods (cf. High voltage techniques. Ed. D. V. Razevig, Moscow, “Energiya” Publishing House, 1976, p. 285). One of the rods in the prior art arrester is connected to a high-voltage conductor of an electric power line, while the second rod is connected to a grounded structure, for example, to a support (such as a tower or a pole) of the electric power line. In case of the overvoltage, a sparkover gap breaks down, so that a lightning overvoltage current is shunted to the ground, and the voltage applied to the device drops rapidly. In this way, both shunting the lightning current and limiting the overvoltage are attained. However, arc quenching ability of a single gap is small, so that after the termination of the overvoltage, a power arc follow current continues to flow through the sparkover gap. Therefore, a shut-off device must be activated for breaking a circuit, such breaking being quite undesirable for consumers receiving electric power from this electric line.
There is further known an arrester that differs from the above-described one in that a third, intermediate rod electrode is placed between a first main rod electrode and a second main rod electrode (cf., for example, U.S. Pat. No. 4,665,460, H01T 004/02, 1987). Thus, instead of a single sparkover air gap, two such gaps are formed. This feature made it possible to improve somewhat arc quenching ability of the arrester and to ensure, with the aid of the arrester, quenching of moderate follow currents (of the order of tens amperes) in cases of single phase-to-ground short circuits. However, this arrester is unable to quench currents exceeding 100 A, which currents are typical for two- or three-phase-to-ground short circuits in lightning overvoltage cases.
As the closest prior art for the invention, an arrester intended for the lightning protection of elements of electrical facilities or an electric power line and supplied with a so-called multi-electrode system (MES) disclosed in RU 2299508, H02H 3/22, 2007 may be indicated. The prior art arrester comprises an insulating body made of a solid dielectric, two main electrodes mechanically coupled to the insulating body, and also two or more intermediate electrodes. The intermediate electrodes, which are arranged between the main electrodes, are mutually displaced, at least, along the longitudinal axis of the insulating body. They are configured to enable a streamer discharge to occur between each of the main electrodes and the intermediate electrode adjacent to said each of the main electrodes, as well as between adjacent intermediate electrodes.
Owing to breaking a distance between the main electrodes into a plurality of sparkover gaps, this arrester possesses a higher arc quenching ability than devices with a single discharge gap or with just a few of such gaps (cf. for example, A. C. Taev. Electric arc in low voltage apparatuses, Moscow, “Energiya” Publishing House”, 1965, p. 85).
Nevertheless, the arc quenching ability of the prior art arrester is not high enough, so that its application is limited to the lightning protection of the HEPLs of voltage class 6-10 kV. Such arrester is difficult to use in the lightning protection of the HEPLs of higher voltage classes for the reason the number of the intermediate electrodes and the arrester size become too large.